1. Field of the Invention
The invention relates to a circuit device and a method for manufacturing the same, and more particularly relates to a circuit device incorporating a power semiconductor element that performs switching of a large current and a control element for controlling the semiconductor element and to a method for manufacturing the same.
2. Description of the Related Art
A structure of a conventional hybrid integrated circuit device 100 is described with reference to FIG. 9. This technology is described for instance in Japanese Patent Application Publication No. Hei 5-102645. A conductive pattern 103 is formed on a surface of a rectangular substrate 101 with an insulative layer 102 interposed therebetween. A certain electrical circuit is formed by fixedly attaching circuit elements on the conductive pattern 103. Here, a semiconductor element 105A and a chip element 105B as the circuit elements are connected to the conductive pattern 103. Leads 104 are connected to pads 109 each formed of a part of the conductive pattern 103 at a peripheral portion of the substrate 101 and function as external terminals. An encapsulating resin 108 has a function of encapsulating the electrical circuit formed on the surface of the substrate 101.
The semiconductor element 105A is a power element through which a large current of about several to several hundreds of amperes flows for example and thus generates an extremely large amount of heat. Thus, the semiconductor element 105A has been placed on an upper portion of a heat sink 110 placed on the conductive pattern 103. The heat sink 110 is made of a piece of metal such as copper having a size of about length×width×thickness=10 mm×10 mm×1 mm for example.
The hybrid integrated circuit device 100 having the structure incorporates, for example, an inverter circuit that generates a large amount of heat during operation. Still, the large amount of heat generated when the inverter circuit converts direct-current power of a large current into alternate-current power is favorably radiated outside through the substrate 101.
However, for the hybrid integrated circuit device 100 having the structure, a control element for controlling switching of the semiconductor element 105A needs to be prepared separately from the hybrid integrated circuit device 100 and this leads to a high cost. The control element may be mounted on the upper surface of the circuit board 101 together with the semiconductor element 105A. Unfortunately, in this structure, the heat generated by the semiconductor element 105A may be transmitted to the control element through the substrate 101 having an excellent thermal conductivity. Thus, the control element may be overheated and malfunction.
In addition, to form a circuit such as the inverter circuit for converting a large current on the upper surface of the substrate 101, the conductive pattern 103 needs to be wide to secure a current capacity. Thus, downsizing of the hybrid integrated circuit device 100 is hindered.